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By Joe Kiolbasa, Donaldson Torit Product Manager
There have been many articles published that focus on advances in industrial dust collector filters, but the lion’s share of them focused on dust collectors using cartridge filters. While collectors with cartridges offer many advantages, there are thousands of facilities in North America still buying and operating baghouses. This paper addresses the filtration needs of these baghouse owners and operators.
Baghouse filters can be made of a wide variety of materials. If the airstream going into the collector is above 275°F then P84, Aramid, Ryton and other materials can be considered. If there is high moisture content in the airstream, as when filtering air from dryers, or if high acid or alkali conditions exist in the air stream, polypropylene may be an option. But each of these applications is special, requiring bags made of special materials.
For most applications, common polyester has been the media of choice in baghouse filters because it does an acceptable job of filtering air, it lasts an acceptable period of time, and the first installed cost is economical. There is, however, another type of polyester bag filter that can provide better baghouse performance and still do it economically. These bags are made of hydroentangled polyester, and following are the top five reasons to consider them:
Lab and field results have consistently shown hydroentangled bags last longer due to better surface-loading and pulse cleaning. In fact, hydroentangled bags have been known to last two to three times longer than common polyester bag filters.
3. Reduced Emissions – Looking at the previous pressure drop chart, one might assume that it is easier for air to pass through the hydroentangled bags and, therefore, more dust must be getting through these bags too. But that is not the case. Hydroentangled bag filters actually emit up to 30% fewer particle emissions than common needled felt bag filters on particles 2.5 microns and smaller. Again, this is due to hydroentangled polyester’s smaller pores and more uniform material. This can be a big benefit to plant managers using baghouses to keep their facilities clean and to meet EPA emissions standards.
4. Reduced Energy Costs – Another benefit of the surface-loading and lower pressure drop of hydroentangled bags is the reduced fan energy used to draw air through the baghouse. Fans will not have to work as hard because there is less restriction in the bag filters. Further, if fans are equipped with an EISA-compliant motor and use a variable frequency drive, the annual energy savings can be quite dramatic. The example below shows energy consumption reduced by over $6,000 per year using hydroentangled bags on one collector with 484 bags. Obviously, the more collectors a facility has, the greater the potential energy savings.
5. Reduced Maintenance Costs – One of the least favorite jobs a plant employee has to do is replace bag filters in a baghouse. It’s a dusty, dirty job and, depending upon the time of year, it might need to be done in extremely hot or cold weather conditions. In addition to being unpleasant, it can be costly to the company that owns the baghouse. Often times this work has to be done when the plant is not running since the baghouse needs to be turned off while the bag filters get replaced. This can result in weekend or holiday labor rates, which make the project even more expensive.
Field experiences have shown hydroentangled bag filters can last two to three times longer than needled felt polyester bags when replacement is due to excessively high pressure drop. Assuming hydroentangled bags last twice as long as needled felt bags and factoring in labor and bag costs, a plant could save more than $3,500 each time its employees replace hydroentangled bags in a 484 bag baghouse. Once again, if a facility has multiple baghouses, the savings can add up quickly.
Many companies are still using baghouses to keep their facilities clean. By asking for hydroentangled felt baghouse bags, plant managers can keep their facilities cleaner while reducing their energy and maintenance costs.